In the U.S. Pat. No. 5,268,695 issued to Dentinger et al., a system for time multiplexing a carrier signal received by two or more GPS antennas through a single hardware path was disclosed. This patent is incorporated in the current patent application by reference in its entirety.
In the best mode of the system of '695 patent four GPS antennas were utilized, one Master antenna and three Slave antennas. The code and carrier measurements were performed by using the Master antenna in order to compute the position, velocity and time coordinates (PVT) of the system. On the other hand, the carrier phase measurements were performed by using three Slave antennas in order to compute the attitude (ATT) of the system. All four antennas were time multiplexed in order for a received carrier signal to enter a single hardware path. Thus, the PVT measurements were performed in the system of '695 patent using the Master antenna only 25% of the overall time spent on all measurements. This caused a reduction in the available carrier-to-noise ratio (C/N.sub.0) in the system of '695 patent as compared to a system where a Master antenna uses all 100% of its time on PVT measurements.
The ability to track signals with lower (C/N.sub.0) values results in enhanced system performance in low (C/N.sub.0) situations such as high dynamics, jamming environments, and low elevation satellites.
What is needed is a system of differential phase measurement employing a plurality of GPS antennas with enhanced antenna multiplexing for attitude determination that has extended carrier-to-noise ratio (C/N.sub.0) performance and is adequate for high dynamics and low signal availability applications.